CVE-2026-97615

In the Linux kernel, the following vulnerability has been resolved:

net: bridge: use option bits for CFM/MRP frame handlers

CFM and MRP register a global br frame type whose hlist node is linked into the per-bridge frame type list when the first MEP/MRP instance is created. Enabling the protocol on multiple bridges therefore inserts the same node into multiple lists. Unregistering it on one bridge then corrupts list state belonging to another.

These handlers can only be installed once per bridge, and they are uncommon. Track their per-bridge enable state with net bridge option bits, which already live on the Rx hot cache line, and dispatch the matching handler directly from the receive path. Check both bits together first as an unlikely case.

Remove the generic frame type list and br frame type helpers, which have had no other users since CFM and MRP were added. That shrinks struct net bridge by 8 bytes and drops the list walk from the fast path. When neither protocol is compiled in, BR CFM MRP OPTS is 0 and the compiler prunes the branch.